net: filter: keep original BPF program around
In order to open up the possibility to internally transform a BPF program
into an alternative and possibly non-trivial reversible representation, we
need to keep the original BPF program around, so that it can be passed back
to user space w/o the need of a complex decoder.
The reason for that use case resides in commit a8fc927780
("sk-filter:
Add ability to get socket filter program (v2)"), that is, the ability
to retrieve the currently attached BPF filter from a given socket used
mainly by the checkpoint-restore project, for example.
Therefore, we add two helpers sk_{store,release}_orig_filter for taking
care of that. In the sk_unattached_filter_create() case, there's no such
possibility/requirement to retrieve a loaded BPF program. Therefore, we
can spare us the work in that case.
This approach will simplify and slightly speed up both, sk_get_filter()
and sock_diag_put_filterinfo() handlers as we won't need to successively
decode filters anymore through sk_decode_filter(). As we still need
sk_decode_filter() later on, we're keeping it around.
Joint work with Alexei Starovoitov.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
f8bbbfc3b9
commit
a3ea269b8b
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@ -19,14 +19,19 @@ struct compat_sock_fprog {
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};
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#endif
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struct sock_fprog_kern {
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u16 len;
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struct sock_filter *filter;
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};
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struct sk_buff;
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struct sock;
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struct sk_filter
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{
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struct sk_filter {
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atomic_t refcnt;
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u32 jited:1, /* Is our filter JIT'ed? */
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len:31; /* Number of filter blocks */
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struct sock_fprog_kern *orig_prog; /* Original BPF program */
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struct rcu_head rcu;
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unsigned int (*bpf_func)(const struct sk_buff *skb,
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const struct sock_filter *filter);
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@ -42,14 +47,20 @@ static inline unsigned int sk_filter_size(unsigned int proglen)
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offsetof(struct sk_filter, insns[proglen]));
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}
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#define sk_filter_proglen(fprog) \
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(fprog->len * sizeof(fprog->filter[0]))
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extern int sk_filter(struct sock *sk, struct sk_buff *skb);
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extern unsigned int sk_run_filter(const struct sk_buff *skb,
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const struct sock_filter *filter);
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extern int sk_unattached_filter_create(struct sk_filter **pfp,
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struct sock_fprog *fprog);
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extern void sk_unattached_filter_destroy(struct sk_filter *fp);
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extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
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extern int sk_detach_filter(struct sock *sk);
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extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
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extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
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extern void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to);
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@ -629,6 +629,37 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
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}
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EXPORT_SYMBOL(sk_chk_filter);
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static int sk_store_orig_filter(struct sk_filter *fp,
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const struct sock_fprog *fprog)
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{
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unsigned int fsize = sk_filter_proglen(fprog);
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struct sock_fprog_kern *fkprog;
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fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL);
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if (!fp->orig_prog)
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return -ENOMEM;
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fkprog = fp->orig_prog;
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fkprog->len = fprog->len;
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fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL);
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if (!fkprog->filter) {
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kfree(fp->orig_prog);
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return -ENOMEM;
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}
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return 0;
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}
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static void sk_release_orig_filter(struct sk_filter *fp)
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{
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struct sock_fprog_kern *fprog = fp->orig_prog;
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if (fprog) {
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kfree(fprog->filter);
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kfree(fprog);
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}
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}
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/**
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* sk_filter_release_rcu - Release a socket filter by rcu_head
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* @rcu: rcu_head that contains the sk_filter to free
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@ -637,6 +668,7 @@ void sk_filter_release_rcu(struct rcu_head *rcu)
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{
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struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
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sk_release_orig_filter(fp);
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bpf_jit_free(fp);
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}
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EXPORT_SYMBOL(sk_filter_release_rcu);
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@ -669,8 +701,8 @@ static int __sk_prepare_filter(struct sk_filter *fp)
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int sk_unattached_filter_create(struct sk_filter **pfp,
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struct sock_fprog *fprog)
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{
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unsigned int fsize = sk_filter_proglen(fprog);
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struct sk_filter *fp;
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unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
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int err;
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/* Make sure new filter is there and in the right amounts. */
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@ -680,10 +712,16 @@ int sk_unattached_filter_create(struct sk_filter **pfp,
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fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL);
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if (!fp)
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return -ENOMEM;
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memcpy(fp->insns, fprog->filter, fsize);
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atomic_set(&fp->refcnt, 1);
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fp->len = fprog->len;
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/* Since unattached filters are not copied back to user
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* space through sk_get_filter(), we do not need to hold
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* a copy here, and can spare us the work.
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*/
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fp->orig_prog = NULL;
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err = __sk_prepare_filter(fp);
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if (err)
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@ -716,7 +754,7 @@ EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
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int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
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{
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struct sk_filter *fp, *old_fp;
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unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
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unsigned int fsize = sk_filter_proglen(fprog);
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unsigned int sk_fsize = sk_filter_size(fprog->len);
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int err;
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@ -730,6 +768,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
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fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL);
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if (!fp)
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return -ENOMEM;
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if (copy_from_user(fp->insns, fprog->filter, fsize)) {
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sock_kfree_s(sk, fp, sk_fsize);
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return -EFAULT;
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@ -738,6 +777,12 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
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atomic_set(&fp->refcnt, 1);
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fp->len = fprog->len;
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err = sk_store_orig_filter(fp, fprog);
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if (err) {
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sk_filter_uncharge(sk, fp);
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return -ENOMEM;
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}
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err = __sk_prepare_filter(fp);
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if (err) {
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sk_filter_uncharge(sk, fp);
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if (old_fp)
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sk_filter_uncharge(sk, old_fp);
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return 0;
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}
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EXPORT_SYMBOL_GPL(sk_attach_filter);
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@ -769,6 +815,7 @@ int sk_detach_filter(struct sock *sk)
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sk_filter_uncharge(sk, filter);
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ret = 0;
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(sk_detach_filter);
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to->k = filt->k;
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}
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int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len)
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int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
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unsigned int len)
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{
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struct sock_fprog_kern *fprog;
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struct sk_filter *filter;
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int i, ret;
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int ret = 0;
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lock_sock(sk);
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filter = rcu_dereference_protected(sk->sk_filter,
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sock_owned_by_user(sk));
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ret = 0;
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if (!filter)
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goto out;
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ret = filter->len;
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/* We're copying the filter that has been originally attached,
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* so no conversion/decode needed anymore.
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*/
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fprog = filter->orig_prog;
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ret = fprog->len;
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if (!len)
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/* User space only enquires number of filter blocks. */
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goto out;
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ret = -EINVAL;
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if (len < filter->len)
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if (len < fprog->len)
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goto out;
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ret = -EFAULT;
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for (i = 0; i < filter->len; i++) {
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struct sock_filter fb;
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sk_decode_filter(&filter->insns[i], &fb);
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if (copy_to_user(&ubuf[i], &fb, sizeof(fb)))
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if (copy_to_user(ubuf, fprog->filter, sk_filter_proglen(fprog)))
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goto out;
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}
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ret = filter->len;
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/* Instead of bytes, the API requests to return the number
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* of filter blocks.
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*/
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ret = fprog->len;
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out:
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release_sock(sk);
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return ret;
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@ -52,9 +52,10 @@ EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);
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int sock_diag_put_filterinfo(struct user_namespace *user_ns, struct sock *sk,
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struct sk_buff *skb, int attrtype)
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{
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struct nlattr *attr;
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struct sock_fprog_kern *fprog;
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struct sk_filter *filter;
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unsigned int len;
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struct nlattr *attr;
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unsigned int flen;
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int err = 0;
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if (!ns_capable(user_ns, CAP_NET_ADMIN)) {
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}
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rcu_read_lock();
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filter = rcu_dereference(sk->sk_filter);
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len = filter ? filter->len * sizeof(struct sock_filter) : 0;
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if (!filter)
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goto out;
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attr = nla_reserve(skb, attrtype, len);
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fprog = filter->orig_prog;
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flen = sk_filter_proglen(fprog);
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attr = nla_reserve(skb, attrtype, flen);
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if (attr == NULL) {
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err = -EMSGSIZE;
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goto out;
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}
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if (filter) {
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struct sock_filter *fb = (struct sock_filter *)nla_data(attr);
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int i;
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for (i = 0; i < filter->len; i++, fb++)
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sk_decode_filter(&filter->insns[i], fb);
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}
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memcpy(nla_data(attr), fprog->filter, flen);
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out:
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rcu_read_unlock();
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return err;
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